This invention relates to a heat exchanger for transfer of heat from an array of electronic circuit chips and, more particularly, to a flexible sheet having cooling fins thereon to be placed directly on the array of chips.
Arrays of electronic circuit chips are interconnected to provide vast electronic circuits. Such circuits may be employed in computers and other electronic systems utilizing very large numbers of electronic circuit components. In particular, it is noted that the many transistors and other circuit components present within a circuit chip dissipate heat in response to activation with current from an electric power supply. In order for the circuits to function properly, the heat must be removed to maintain proper operating temperature for the circuits.
One form of cooling which has been proposed is the use of a metal plate held against circuit chips by springs, as is disclosed by Cutchaw (U.S. Pat. No. 4,381,032). Another form of heat exchanger for cooling electronic circuits provides for passages within which liquid coolant is circulated, the coolant contacting a flexible wall which presses against the circuitry to be cooled as shown in Wilson et al, U.S. Pat. No. 4,072,188. Another form of heat exchanger employs coated metallic dendrites which are held by springs against a circuit chip as disclosed in Babuka et al, U.S. Pat. No. 4,254,431. Yet another form of heat exchanger employs a pillow structure formed of film and filled with a thermal liquid material for extracting heat from an electric circuit, as is disclosed in Spaight, U.S. Pat. No. 4,092,697. Also a malleable dimpled wafer is deformed by pressure between a heat source such as an electronic circuit and a heat sink, as is disclosed in Rhoades et al, U.S. Pat. No. 4,151,547. A theoretical discussion of cooling considerations is presented in an article in the IEEE Electron Devices Letters, "High Performance Heat Sinking For VLSI" by D. B. Tuckerman and R. F. W. Pease, Vol. EDL-2, No. 5, May 1981.
A problem arises in that the foregoing heat-exchanger structures are either complex, or require complex manufacturing procedures in assembling the heat exchanger with the electric circuits to be cooled. In view of the large number of circuit chips to be employed in an electronic system, and the small size of the chips which are on the order of approximately a few millimeters square, any reduction in the complexity of the heat exchanger and in the assembly procedures can significantly reduce manufacturing costs, and may even permit the use of still higher power dissipation in the electric circuits. Presently available heat exchangers do not provide these advantages.